| eyeball(verb, study, mark, consider, see) |
| find out(verb, expression, phrasal verb, activity, detect) |
| foreign agent(noun, expression, person, plant, mole) |
| identify(verb, consider, see, note, regard) |
| intelligence agent(noun, expression, idiom) |
| mind(noun, mark, consider, see, respect) |
| note(noun, verb, mark, consider, see) |
| patrol(noun, verb, person, plant, watch) |
| scrutinize(verb, study, mark, consider, sound) |
| sense(noun, verb, see, observe, notice) |
| spotter(noun, person, plant, watch, guard) |
| stake out(verb, expression, phrasal verb, study, consider) |
| traitor(noun, person, opposition, agent, villain) |
| undercover(adjective, secret, hidden, covert) |
| assassin(noun, opposition, agent, villain, rebel) |
| counterspy |
| eye(noun, verb, consider, see, respect) |
| fish out(verb, expression, phrasal verb, follow, discover) |
| follow(verb, see, note, regard, observe) |
| intelligencer(noun, person, plant, mole, sleeper) |